No guarantee that this is up to date[1] (or even error free).
I realize that Github Gists are also not Open Source, but they render without Javascript enabled, and Simplenote was acting up for me and wouldn't let me publish.
would you be willing to pay for a proxy service that took a url that used non-free JS and rendered it to pure dom that you could then view without JS ?
any sense of whether other people that care about such things would be willing to pay ?
Interesting idea, but I don't think anyone would pay for it. From a freedom perspective it would probably be considered SaaSS[0]. You could use wkhtmltopdf[1] for a service like that.
[1]: https://www.gnu.org/philosophy/javascript-trap.html